Change OptionValueFileSpec::SetValueFromCString to strip off whitespace,
single-quote and double-quotemarks from around file paths specified to
settings like target.expr-prefix or target.process.python-os-plugin-path.
<rdar://problem/14970457> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@190654 91177308-0d34-0410-b5e6-96231b3b80d8